The present embodiments relate to a patient couch for a magnetic resonance tomography system having a plug-in connector for a local coil.
Magnetic resonance tomography systems are imaging devices that, in order to image an object under examination, align nuclear spins of the object under examination with a strong external magnetic field and excite the nuclear spins by an alternating magnetic field to precess about the alignment. The precession or return of the spins from the excited state to a state with a lower energy in turn generates an alternating magnetic field as a response (e.g., a magnetic resonance signal) that is received via antennas.
With the aid of magnetic gradient fields, a position encoding that subsequently enables an association of the received signal with a volume element is imparted to the signals. The received signal is then evaluated, and a three-dimensional imaging display of the object under examination is provided.
In order to excite the precession of the spins, alternating magnetic fields having a frequency that corresponds to the Larmor frequency at the respective static magnetic field strength and having very high field strengths or power levels are to be provided. In order to improve the signal-to-noise ratio of the magnetic resonance signal received by the antennas, antennas frequently referred to as local coils that are arranged directly on the patient are used.
In the case of high magnetic fields (e.g., at 3 T and greater), Larmor frequencies of greater than 100 MHz result. At these frequencies, the absorption in the human body increases significantly at the same time interference effects results at the wavelengths of 2 m and less within the area occupied by the patient in the patient tunnel. This provides that a homogeneous field strength of the exciting alternating magnetic field B1 and thus a homogeneous excitation with a single body coil surrounding the body is no longer ensured.
In order to avoid image artifacts caused thereby, local coils with transmit coils that are arranged individually or as an array on the body in the immediate vicinity of a region under examination are also used. The transmit coils, however, are not to be supplied with radiofrequency energy of the excitation signal to be sent, which attains power levels of several hundred watts up to kilowatts. A low-loss transmission of the power level provides that correspondingly thick coaxial cables that are then also correspondingly rigid and difficult to handle are used.